Process of preparing fine-grained blends of lead with copper or aluminum

ABSTRACT

FINE-GRAINED ALLOYS OF METALS SUCH AS LEAD AND COPPER OR LEAD AND ALUMINUM ARE MADE BY MELTING THE INDIVIDUAL METALS SEPARATELY UNDER REDUCTION CONDITIONS AND MIXING THEM INTIMATELY UNDER REDUCTION CONDITIONS AND THEN CASTING THEM OR EXTRUDING THEM IMMEDIATELY THEREAFTER.

U.S. Cl. 75-135 United States Patent 3,743,502 Patented July 3, 1973PROCESS OF PREPARING FIN E-GRAINED BLENDS OF LEAD WITH COPPER ORALUMINUM Ernest Hey, Eureka, Califi, assignor to Helen B. Sherry,Seattle, Wash. No Drawing. Filed Apr. 29, 1971, Ser. N 138,785 Int. Cl.C22c 1/02, 1/06 14 Claims ABSTRACT OFv THE DISCLOSURE Fine-grainedalloys of metals such as lead and copper or lead and aluminum are madeby melting the individual metals separately under reduction conditionsand IlllXlIlg them intimately under reduction conditions and thencasting them or extruding them immediately thereafter.

This invention relates to improvements in the alloying and blending ofmetals. It has particular applicability to blends of lead and copper andto blends of lead and aluminum, but it applies also to many othermetals.

Lead and copper do not blend in the sense of fusing together, nor dolead and aluminum. The same is true of many other metals. They only meltand alloy or bond. This results in many flaws and in rather coarsegraining.

In contrast, the present invention obtains uniform homogeneous mixturesor blends of such metals in practically any proportion. This blending isaccomplished by creating an affinity between different metals. It is achemical blend, not a mere mechanicalbond.

For example, lead cannot ordinarily be blended with copper or aluminum,while still having a uniform dispersion of the lead throughout thealloy, because after the lead reaches a certain rather low percentage,it tends to concentrate itself in clusters called dendrites. In contrastthe present invention is able to provide blends free from a substantialnumber of such clusters, or even entirely free from them. Thus, forexample, in a blend of about 60% copper and 40% lead made according tothis invention, microphotograph taken of a cross-section of the samplewas magnified 175 times and showed uniform homogeneous diffusion ordispersion of the lead throughout the copper. Such uniformity of blendhas not been obtainable prior to the present invention.

The same thing has been done with lead and aluminum, which have suchdifferent specific gravities that they are quite difiicult to mixtogether well. The present invention provides blends that will notseparate upon casting or extruding. The invention also applies to blendsof magnesium and lead.

The alloy blends of this invention have various uses depending upon theparticular compositions. For example, the copper-lead product of thisinvention can be used in journal-bearings and provides the type oflubrication that can overcome the hot-box problem on railroad journals.The metal blend is nonporous and is substantially self-lubricatinghaving even a greasy feel, and can therefore give superior results as ajournal bearing with graphite or oil.

The invention may also be used to produce superior bronzes which are notporous and do not leak and to produce zinc-free brasses.

Alloys of aluminum can be produced that eliminate the necessity foranodizing or enameling the aluminum.

Other objects and advantages of the invention will appear from thefollowing description of some preferred embodiments.

The metals to be blended according to this invention are firstindividually Weighed out in amounts determined by the proportionsdesired in the finished blend. Then each metal is placed in a separateclean crucible and Bee melted separately, bringing each to its meltingpoint while under a cover of granulated charcoal or other similar carbonat temperatures hot enough to dissolve most insolubles; if anyinsolubles do turn up they should be skimmed 01f.

Since metals have different specific gravities, they tend to separatewhen they are melted together, and one tends to float on top of theother, except to a relatively minor extent. An important purpose of thepresent process is to enable the metals to form a true blend, not justto bond as alloys, and that is why the metals are handled separately atthis stage.

An important feature of the invention is to agitate each of these melts,for example, either by stirring each deeply with treated wooden sticksor by swirling each crucible. For stirring, the wood may be hardwood,either seasoned or green, and it should be specially treated. Thepreferred treatment is to soak the hardwood stick in a solution of lyeand then to dry it. For even better results, it should be re-soaked anddried again. Of course, the stick should be completely dry and hotbefore it is used to stir the liquid metal, so that it will not causethe liquid metal to explode. After this stirring, the separate solutionsshould be again skimmed; and it is advisable at this stage to sprinklepowdered lye or other powerful alkaline on the charcoal cover, beforemixing the two metals together.

The mixing may then be achieved by pouring one crucible into anotherback and forth several times, to obtain a thorough mix and whileagitating by swirling the crucible or by stirring the mix thoroughlywith a similarly treated stick. The heavier metal should preferably bepoured into the lighter metal lead, for example, should be poured intothe copper (or into the aluminum). There is intimate contact between themetal and escaping gases, with the hydrogen obtained from the sodiumhydroxide or other alkali, as well as contact with the carbon or carboncompounds, including resins in the wood, for example. A silicate of aresin may be used instead of the wood, if desired. The important thingis to provide chemical reduction during the time of the mixing as wellas shortly prior to it. The wood chars and some of the carbon combineswith any oxygen present to produce carbon dioxide; hydrogen, if present,also helps to reduce the oxygen present. A charcoal or carbon layer mustbe kept on the hot metal to exclude oxygen from it. Pouring the moltencontent over and through charcoal and lye enables one to getinoculation, a complete homozenizing, or The texture of the metals, andsimilar treatments operating on the same principle can be used instead.

Immediately after mixing, the metal mixture should be poured and set. Itmay be poured into molds to achieve a desired shape. In order to makesure that the process is working satisfactorily, one or more samples maybe broken apart while the alloy is still hot and plastic and still softenough to raise from the mold and to break when twisted, and the metalstructure may thus be inspected. If the process has been correctlyperformed, the structure will look like fine wires throughout themixture, running the full length of the ingot. The alloys of thisinvention have a different crystal formation from other alloys and lookslike fine wires of copper color, the ingot itself also having a coppercolor. To test an ingot or bar after it is cool, some cuts may be madeand the cuts examined.

The metal resulting from this process is superior to bronze and brassand is not affected in the same Way by electrolysis. It can be used toproduce fine bronzes, with or without tin, or fine brass without zinc.It may also be used to make superior solder and does not require silverin a silver solder. The metal is self-lubricating and has a rathergreasy feel in its finished state because of this lubricative nature.These blends tend to be self protective against bruises and replacethemselves if scarred or bruised.

As examples, very fine-grained alloys of copper and lead, with copper ashigh as 40% and with 60% lead have been made. A particular example was61.02% copper, 38.75% lead, with the remainder being other metals orimpurities. In other instances, 70%30% mixes have been :made. Anypercentage of copper and any percentage of lead can be used. The sameproportions and similar proportions apply to copper-aluminum blends,leadaluminum blends, and magnesium-lead blends.

A blend of 97.5% lead and 2.5% copper made accord ing to this inventionmakes an excellent material for covering or cladding wire cable, for itacts like a grease for the wire, when the wire is under strain andfriction develops between Wires. Iron plates and bolts clad or plated bythis blend are less subject to corrosion.

The blends of lead and copper made according to this invention haveanother remarkable property. When such a blend has been molded orextruded and cooled, it can be cut or sawed into, and the freshly cutsurface appears as a silvery color, while the outside, uncut surface hasa coppery color. After the cut surface has been exposed to theatmosphere for a short time, it takes on a coppery or brass-likesurface. If this surface is filed off, the silvery color reappears, andthis, too, becomes coppery after exposure to oil or water or air, and soon.

If the blend of this invention is remelted and poured again without thetreatment of this invention, dendrites form throughout the cold ingot.

I claim:

1. Preparing a fine-grained blend of lead with metal chosen from thegroup consisting of copper and aluminum, comprising the steps of:

(a) separately melting each metal,

(b) maintaining each metal under chemical reduction conditions,

(c) mixing the metals together thoroughly while subjecting the mixtureto chemical reduction, and

'(d) immediately pouring the mixture and hardening it.

2. The process of claim 1 wherein said chemical reduction conditionsinclude a cover of carbon over each metal during and after melting.

3. The process of claim 2 wherein said chemical reduction conditionsalso include stirring each metal with a carboniferous stick beforemixing and stirring the mixture during the mixing.

4. The process of claim 3 wherein said stick is hardwood that has beensoaked in a lye solution and then thoroughly dried.

5. The process of claim 3 wherein said cover of carbon additionallycontains an alkali hydroxide.

6. The process of claim 5 wherein said alkali hydroxid is sodiumhydroxide.

7. The process of claim 2 wherein the metals are mixed while agitatingand swirling them together.

8. The process of claim 1 wherein the heavier metal is poured into thelighter metal at the mixing step.

9. A process for making a fine-grained blend of copper and lead,comprising the steps of:

(a) weighing each metal out in an amount needed to provide desiredpreparations in the blend,

'4 (b) separately melting each metal in a separate crucible, (c) whilecovering each metal with a layer of charcoal, 4 (d) stirring each metal,when it has melted, with a wooden stick,

(e) adding to each charcoal layer an amount of lye,

(f) pouring the molten lead into the molten copper, While stirring witha wooden stick and while main taining the charcoal-lye cover,

(g) mixing the molten metals thoroughly, and

(h) then immediately pouring the mixture and cooling 10. The process ofclaim 9 wherein said step (g) includes pouring the mixture back andforth between crucibles.

11. The process of claim 9 wherein said wooden stick has previously beensoaked in a lye solution and thereafter thoroughly dried.

12. A process for making a fine-grained blend of aluminum and lead,comprising the steps of:

(a) weighing each metal out in an amount needed to provide desiredpreparations in the blend,

(b) separately melting each metal in a separate graphite crucible, v

(0) while covering each metal with a layer of charcoal,

(d) stirring each metal, when it has melted, with a wooden stick,

'(e) adding to each charcoal layer an amount of lye,

(f) pouring the molten lead into the molten aluminum,

while stirring with a wooden stick and while maintaining thecharcoal-lye cover,

(g) mixing the molten metals thoroughly, and

(h) then immediately pouring the mixture and cooling it. 13. The processof claim 12 wherein said step (g) includes pouring the mixture back andforth between cruciles.

14. The process of claim 12 wherein said wooden stick has previouslybeen soaked in a lye solution and thereafter thoroughly dried.

References Cited UNITED STATES PATENTS L. DEWAYNE RUTLEDGE, PrimaryExaminer E. L. WEISE, Assistant Examiner U.S. c1. X.R., 162, 163, 166 R,166 E

